Averaged cortical evoked responses (AER) in patients with untreated adrenal cortical insufficiency were larger in amplitude and longer in latency than during treatment with carbohydrate-active steroids. Intravenous infusions of ACTH inhibited the AER effect while off treatment suggesting a specific and separate role for ACTH in brain function independent of its role in stimulating adrenocorticosteroid secretion. ACTH, through its effects on sleep patterns has been shown to play a role in the central nervous system which may be, in part, independent of its role in stimulating adrenal steroidogenesis. Decreased thyroid hormone in patients with hypothyroidism and in rats made hypothyroid with I131 has been related to decreased taste acuity and other aberrations of taste. Treatment with thyroid hormone returned these abnormalities to or toward normal in both the patients and the rats. The locus of action of thyroid hormone is either at the taste receptor, the neuraxon or in the central nervous system.